Is a mispronunciation and corruption of the word 'cousin' by those Middle Eastern decent. By referring to a person as 'kez' or 'cousin', the speaker is implying a title and a deal of affection or respect for the person.

A kez is something a women does such as stringing on a man for a long time and making the man fall in love with her whilst she is with another man but when the first man asks if she is with the secound man she will deny but she really is. Or just a women who said she likes a man but then doesnt give herself to him.